Indicia reading terminals for reading decodable indicia are available in multiple varieties. For example, minimally featured indicia reading terminals devoid of a keyboard and display are common in point of sale applications. Indicia reading terminals devoid of a keyboard and display are available in the recognizable gun style form factor having a handle and trigger button that can be actuated by an index finger.
Indicia reading terminals having keyboards and displays are also available. Keyboard and display equipped indicia reading terminals are commonly used in shipping and warehouse applications, and are available in form factors incorporating a display and keyboard. In a keyboard and display equipped indicia reading terminal, a trigger button for actuating the output of decoded messages is typically provided in such locations as to either enable actuation by a thumb of an operator or in some cases also providing a handle and trigger button that can be actuated by the index finger.
Indicia reading terminals in a form devoid of a keyboard and display or in a keyboard and display equipped form are commonly used in a variety of data collection applications including point of sale applications, shipping applications, warehousing applications, security check point applications, and patient care applications, and personal use, common where keyboard and display equipped indicia reading terminal is provided by a personal mobile telephone having indicia reading functionality.
Some indicia reading terminals are adapted to read barcode symbols including one or more of one dimensional (1D) barcodes, stacked 1D barcodes, and two dimensional (2D) barcodes. Other indicia reading terminals are adapted to read optical character recognition (OCR) characters while still other indicia reading terminals are equipped to read barcode symbols, postal symbologies or other information bearing indicia.
Barcode symbols are typically disposed on a substrate such as paper. Recently, barcode symbols are now being displayed on a display screen. Attempts have been made to provide indicia reading terminals capable of reading barcodes on paper and barcodes displayed on a display screen. Liquid crystal displays (LCDs) typically employ one or more polarizers so that the light emitted from the display has a polarized orientation.
There is a need for further optical readers, and in particular for optical readers and methods employing polarization sensing of light from decodable indicia.